The speed necessary to reach port at a designated time... - USCG Navigation Problems

The speed necessary to reach port at a designated time is 18.7 knots. The propeller pitch is 24'03", and you estimate 3% positive slip. How many RPM's will the shaft have to turn?

A 81 RPM

B 98 RPM

C 104 RPM

D 87 RPM

AI Explanation

The correct answer is A) 81 RPM. To calculate the required RPM, we can use the formula: RPM = (Speed in knots x 1.6889) / (Propeller Pitch in feet). Given: - Speed = 18.7 knots - Propeller Pitch = 24.05 feet (24'03" converted to feet) - Positive slip = 3% Accounting for the positive slip, the actual speed is 18.7 / (1 - 0.03) = 19.28 knots. Plugging these values into the formula: RPM = (19.28 x 1.6889) / 24.05 = 81 RPM The other options are incorrect because they do not correctly apply the formula and account for the given propeller pitch and positive slip.

Question 27Navigation Problems

The speed necessary to reach port at a designated time is 18.7 knots. The propeller pitch is 24'03", and you estimate 3% positive slip. How many RPM's will the shaft have to turn?